1. Field of the Invention
The present invention relates to a cooling system for an onboard electrical power converter that is mounted to an electric automobile, a hybrid automobile, or a railway vehicle or the like, and to an electrical power converter for a railway vehicle.
2. Description of Related Art
With an electric automobile, a hybrid automobile, or a railway vehicle, a motor is provided in order to serve as a source of motive power, and an electrical power converter such as an inverter or the like is provided in order to control the electrical power supplied to this motor. Such an electrical power converter typically includes a power module that includes power semiconductors such as IGBTs (Insulated Gate Bipolar Transistor) or the like, a drive circuit for driving that power module, a control circuit for controlling it, and one or more capacitors for current smoothing.
It is necessary to cool the electronic components used in this circuitry, since they are vulnerable to high temperatures. Systems provided with electrical power converter that generate great amounts of heat, and that are provided with cooling systems employing the method commonly termed “two-phase thermosyphon cooling system”, are disclosed in the specifications of Japanese Patent No. 3,646,474 and Japanese Patent No. 3,513,846. With the two-phase thermosyphon cooling system, a cooling chamber or a sealed system that is built to circulate a coolant liquid and so provide liquid cooling is charged with coolant whose physical state is in liquid-vapor two phase, that is, the physical state can change between the vapor phase and the liquid phase.